Recently I picked up a set of cds which included among other things a mirror
of Sunsite's Linux ftp site.  It is split across four cds, with the filesystem
by directories.  I actually have five SCSI cdroms at my disposal for an 
extended length of time, and would like to union mount the four discs 
somewhere.  Unfortunately, it seems that union mounts are only designed
to go one layer deep.  

Any ideas what it would take to make this work?  TIA.